Apparatus for exhausting incandescent lamps.



R. LE ROSSIGNOL.

APPARATUS FOR EXHAUSTING INCANDESCENT LAMPS.

APPLICATION FILED JAN. 30' I917- I Patented Mar. 25,1919.

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obert UNITED STATES PATENT oEE1cE. 7

ROBERT LE ROSSIGNOL, OF BERLIN, GERMANY, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

APPARATUS FOR EXHAUSTING INCANZDESCENT LAMPS.

Specification of Letters Patent.

Patented Mar. 25, 1919.

Application filed January 30, 1917. Serial No. 145,563.

. Lamps, of which the following is a specification.

My invention relates to evacuating incandescent electric lamps and similar glass vessels and more particularly to apparatus for exhausting such vessels.

The object of my invention is to simplify and shorten the process of exhausting incandescent lamps and similar vessels. Another object is to provide means by which a large number of lamps may be exhausted and sealed at the same time. Still another object is to do away with the'special long exhaust tube now commonly used, and also to avoid the use of any special devices, such as check valves or non-return valves, in the apparatus used for exhausting. To this end and in accordance with my invention the operation of exhausting the lamps is carried on in a vacuum chamber containing a large number of lamps, each having a short open ended tubulature, and after the chamber and the lamps in it have been exhausted the free ends of the tubulatures are sealed within the exhausted chamber in some suitable manner, as for example, by means of electricity. As compared with the method of sealing the individual lamps one after another by a gas flame as has heretofore been done, my invention has the advantage that a large number of lamps may be sealed at the same time and while they are inside the exhausted vacuum chamber. In this way the entire process of exhausting and sealmg the lamps is simplified nd shortened. The sealing of the lamps may be facilitated and accelerated by providing at the open ends of the tubulatures a small amount of glass which is of lower melting point than the glass of the lamp and which when softened.

or fused by electric heating seals the tubulature. I may also, in accordance with my invention, preheat the lamps to the same or nearly the same temperature as that to which they are raised during exhaust by heating them, for example, in a suitable furnace before putting them into the vacuum chamber. Since by my invention the development of strains or distortion forces in the lamps during the heating in the receptacle is avoided and the pressure inside and outside the lamps is equalized during the exhaust, the incandescent lamps while being exhausted may be heated almost-to the softening temperature'of glass without danger of breakage or of the lamp collapsing.

An apparatus which serves well for carrying out my novel method of exhaustion com, prises, in accordance with my invention, an electrically heated receptacle which is connected to the air pump, electrically heated surfaces mounted in the receptacle, and one or more frames or supports for holding the lamps in place in the" receptacle and in proper relation to the heated surfaces. The arrangement is such that the open ends of the tubulature's which are to be closed by melting are in thermal relation to the heating surfaces and the end of each tubulature may either rest upon a corresponding electrically heated surface even during the operation of exhaustion, or may be held out of contact with the heating surfaces but so close to them that the radiant heat melts down and seals' the ends of the tubul'atures without actual contact with the heated surfaces.

My invention will best be understood 1n connection with the accompanying draw ng in which, merely for purposes of illustration, I show one form of embodiment of my invention suitable for exhausting incandescent lamps, and in which Figure 1 isa longitudinal section of the apparatus, Iflg. 2 a cross section and Fig. 3 a detailed view of a slight modification.

In the particular form of apparatus shown in the drawing, the lamps are exhausted in a double walled vacuum chamber of which the outer wall is formed by a base plate a and a bell or open ended receptacle 6 which may be seated on the base to form a closed chamber and which has a flange on the edge with a cooling pipe 0. An inner bell or globe at is mounted within and is affixed to the receptacle 6 to form with it a which may be connected to a separate exhaust pipe if desired extends through the base plate and terminates at its upper end in a plate Z which goes inside the inner bell d. The pipe 72. also carries below the plate 2 a larger plate i with an annulargroove 70 containing an easily fusible metal of low vapor pressure, such as an alloy of tin and lead. When the double walled cup is in place on the base plate a, the lower edge of the inner bell or globe d dips into the melted metal in the annular groove and makes a hermetical seal so that the plate Z is inclosed in an inner" vacuum chamber which is formed by the bell 03 and the plate 2' and which may be exhausted at will through the one contact block to the other will pass through the heating plate and raise it to the temperature necessarv to meltand close the open ends of the tubulatures of the lamps.

Current is supplied to the contact blocks m and n and to the heating plates 0 through sultable leads p. In the particular arrangement shown the various pairs of contact blocks'm and n are connected in series but the connections may be madein any other manner desired. The incandescent lamps which are to be exhausted are provided with short open ended tubulatures and are so placed in the exhaust chamber that the open ends of the tubulatures are near and in thermal relation to the. heating deviceso. In some cases thelamps may be so positioned that the open ends of the tubulatures rest with their uneven or obliquely-formed edgesdirectly upon or in contact with the heating plateso. The lamps may also be so posi tioned that as shown in Fig. 3 the open end of the tubulature is close to the heating plate 0 but nevertheless remains perfectly free and unobstructed during the exhaust. This pos1t1on may be maintained during the sealing of the lamps, since the tubulatures may be heated and sealedby radiation only. The lamps are held in position in the exhaust chamber by any suitable form of holder, but the form which I prefer comprises a frame havlng two disks 9 and 1 connected to it by bolts and provided with suitable recesses for holding the lamps.

' The method of exhausting lamps by means of this apparatus is as follows The vacuum chamber is opened by lifting the doublewalled cup formed by the bells b and 01 away from the base plates a and i; The lamps, provided with short open ended tubulatures, are placed in the recesses of the disks 9 and r of the lamp holding frame, with the tubu latures in such a position that their open ends will either rest on the heating plates 0 or else will be in proper thermal relation to the heating plates when the frame is in place in the vacuum chamber. After'the frame and the lamps contained in it are In place the vacuum chamber is closed by putting the bells b and d on the base plates with the edge of the bell 6, making an air-tight joint with the base plate a and the edge of the bell d dipping into the molten metal in the annular groove is of the plate 6. The exhaust tubes 9 and h are then connected to the rough pump and to the fine vacuum pumps by suitable connections and 1n the way the vacuum chamber and all the lamps in it are quickly exhausted to the required degree. During the exhaust the heating coll e is supplied with current through the terminals f. -As soon. as the proper vacuum is obtained the lamps are sealed while still in the vacuum chamber by passing a current of suitable intensity through the heating plates 0 and thereby heating them to the necessary temperature to soften and hermetically seal the open ends of the tubulatures which either rest upon the heatmg plates or are so close to them that when the current is supplied to the plates through the lead wires p the open ends of the tubulatures soften and are sealed. After the lamps have been sealed air is admitted into the vacuum chamber, the double walled cup formed by the bells b .and d is lifted to open the chamber, and then the exhausted and sealed lamps are removed.

The incandescent lamps which are to be exhausted may be arranged in various ways to get a large number of lamps into the acuum chamber.

What I claim as new and desire to se cure by Letters Patent of' the United States, is, v v

1. Apparatus for exhausting incandescent ,electric lamps ha'ving short open ended tuchamber, heating devices mounted inside an exhaust pump, means for heating said said chamber, means for controlling said devices from the outside of said chamber, and

lamp holding frames mounted in said chamber to position the lamps with the open ends of their tubulatures in thermal relation to said heating bodies.

3. In an apparatus for exhausting incanbottom at will the edge of the inner bell submerged in the metal in said annular groove when the bell is in place and the edge of the outer bell making a substantially airtight joint with said bottom when said-cup is in place, means for exhausting the space between said bells, and means for exhausting the inner bell.

4. In an apparatus for exhausting incandescent lamps having short open ended tubulatures, the combination of a vacuum chamber, a supporting plate inside said chamber, electric heating units mounted on said. plate, current supply wires for said heating units leading to the outside of said exhaustion chambenand means for holding the lamps with the open ends of the tubulatures of the lamps in thermal rela tion to said heating units.

5. In an apparatus for exhausting incandescent lamps having short open ended tubulatures, the combination of a bottom plate provided with heating plates for at will melting and sealing the open ends of ,the tubulatures of said lamps, a bell cooperating with said bottom plate tO fOI'II1 a vacuum chamber, an exhaust pump for exhausting said chamber, and lamp holding frames for securing the lamps in position with the open ends of their tubulatures in. thermal relation to said heating plates.

6. Apparatus for exhausting incandescent lamps having short open ended tubulatures, comprising a normally closed vacuum chamber connected to an exhaust pump, heating bodies mounted in said chamber, and means for holding the lamps with the end-s of their tubulatures open to said chamber and in thermal relation to said heating bodies whereby said bodies melt the ends of said tubulatures and seal them while said ends are in said chamber.

7. Apparatus for exhausting incandescent lamps comprising a vacuum chamber, means for exhausting said chamber, means for holding in said chamber an incandescent lamp having an exhaust aperture open to the interior of said chamber, and heating means in said chamber for sealing said exhaust aperture while saidchamber is exhausted. QM.

8. Apparatus for exhausting incandescent lamps comprising a vacuum chamber, means for holding in said chamber a plurality of incandescent lamps each having an exhaust aperture open to the interior of said chamber, means for exhausting said cham ber, and means in said chamber for simultaneously heating and sealing the exhaust apertures of said lamps while the chamber is exhausted.

In witness whereof,'I have hereunto set my hand this 24th day of October, 1916.

ROBERT LE ROSSIGNOL.

Witnesses:

HENRY Hasrnn, ALLEN F. JENNINGS. 

